Compile error caused by case of filename extension

Compile error caused by case of filename extension

[Shriramana Sharma]

When the contents of TESTING.C are:

#include "stdio.h"
void main(void)
{
	printf("\n%d\n", ( -0.25 < 0) ? 2 : 4);
}

Upon trying to compile:

$ gcc -o TESTING TESTING.C
TESTING.C:3: error: ‘::main’ must return ‘int’

Then I changed the file to:

#include "stdio.h"
int main(void)
{
	printf("\n%d\n", ( -0.25 < 0) ? 2 : 4);
	return 1;
}

Then I got:

$ gcc -o TESTING TESTING.C
/tmp/ccEnQk4o.o:(.eh_frame+0x11): undefined reference to 
`__gxx_personality_v0'
collect2: ld returned 1 exit status

But if I change the input file name extension to testing.c or even TESTING.c 
(small letters) no problems were got. Why is this?

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$ date [] CCE +2006-03-25 W12-6 UTC+0530
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Re: Compile error caused by case of filename extension

[B S Srinidhi]

Hi,

On Sat, 2006-03-25 at 13:33 +0530, Shriramana Sharma wrote:
[..]
> $ gcc -o TESTING TESTING.C
> /tmp/ccEnQk4o.o:(.eh_frame+0x11): undefined reference to 
> `__gxx_personality_v0'
> collect2: ld returned 1 exit status
> 
> But if I change the input file name extension to testing.c or even TESTING.c 
> (small letters) no problems were got. Why is this?
> 

From the man page of gcc(1):

file.cc
file.cp
file.cxx
file.cpp
file.CPP
file.c++
file.C
    C++ source code which must be preprocessed. Note that in .cxx, the
last two letters must both be literally x.  Likewise, .C refers to a
literal capital C.

That means, gcc will consider a source file with name TESTING.C to be a
C++ source code. Thus trying to include / link with some special
libraries. 

To compile your TESTING.C, use something like:

$ g++ -o TESTING TESTING.C

It 'll compile correctly.

Hope this helps.

Srinidhi.
-- 
ASCII ribbon campaign ( )         B S Srinidhi
 - against HTML email  X          http://srinidhi.deeproot.co.in
             & vCards / \         DeepRoot Linux

Re: Compile error caused by case of filename extension

[Markus Rechberger]

Hi,

don't use void main() functions.. use int main instead.
The c++ standard defines the return value of main being int, though
compiler also support void.
In general int should be better since other applications could check
for the return value if the application exited successfully or not..

Markus

On 3/25/06, B S Srinidhi <srinidhi-c@deeproot.co.in> wrote:
> Hi,
>
> On Sat, 2006-03-25 at 13:33 +0530, Shriramana Sharma wrote:
> [..]
> > $ gcc -o TESTING TESTING.C
> > /tmp/ccEnQk4o.o:(.eh_frame+0x11): undefined reference to
> > `__gxx_personality_v0'
> > collect2: ld returned 1 exit status
> >
> > But if I change the input file name extension to testing.c or even TESTING.c
> > (small letters) no problems were got. Why is this?
> >
>
> >From the man page of gcc(1):
>
> file.cc
> file.cp
> file.cxx
> file.cpp
> file.CPP
> file.c++
> file.C
>     C++ source code which must be preprocessed. Note that in .cxx, the
> last two letters must both be literally x.  Likewise, .C refers to a
> literal capital C.
>
> That means, gcc will consider a source file with name TESTING.C to be a
> C++ source code. Thus trying to include / link with some special
> libraries.
>
> To compile your TESTING.C, use something like:
>
> $ g++ -o TESTING TESTING.C
>
> It 'll compile correctly.
>
> Hope this helps.
>
> Srinidhi.
> --
> ASCII ribbon campaign ( )         B S Srinidhi
>  - against HTML email  X          http://srinidhi.deeproot.co.in
>              & vCards / \         DeepRoot Linux
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>


--
Markus Rechberger